The feeling of freedom and exuberance experienced after a good run isn’t all endorphins. Researchers from the University of Montreal Hospital Research Centre (CRCHUM) have demonstrated that the phenomenon of ‘runner’s high’ is also associated with dopamine, a neurotransmitter involved with sensations of motivation and happiness. Researchers discovered that the advantages by endurance activity are regulated by leptin, a hormone associated with metabolism. Leptin reduces physical activity via dopamine neurons in the brain.

Cure The Boredom– Leptin And Physical Activity

As explained by Stephanie Fulton, researcher at the CRCHUM and lead author of an article published in the journal Cell Metabolism, leptin is secreted by the adipose tissue and controls feelings of satiety. Its role in physical activity has now been discovered.

“The higher the amount of fat, the higher the amounts of leptin secreted, hence reducing our hunger. Our findings now demonstrate that leptin also plays a significant role in our motivation to run, which might be related to searching for food”.

There appears to be a close link between hormones that regulate feelings of hunger and our urge to exercise. The endurance of mammals, especially humans, is believed to have evolved to develop and enhance their chances of finding food. The present study suggests a dual role of leptin – modulating energy balance and motivating behaviors that are ‘rewarding’ for metabolism, including physical activity.

Establishing The Connection Using Genetically Modified Mice

Researchers examined voluntary wheel running in mice. These animals can run up to seven kilometers in a day. In a lab setting, the physical activity of normal mice was compared with genetically modified mice who were treated to suppress STAT3 (signal transducer and activator of transcription-3), a molecule that is activated by leptin. STAT3 is present in neurons that manufacture dopamine in the mid-brain, and its pathway is similar to a ‘motivational highway’.

“Mice lacking STAT3 in their dopaminergic neurons ran more substantially as compared to normal mice that were seen to be less active. Leptin then activates STAT3 in the dopamine neurons, signaling that the body’s energy stores are adequate and that there is no need to increase physical activity and go looking for food”, explained first author Maria Fernanda Fernandes.

Inferring Similar Findings For Humans

Researchers believe that the findings could be easily extended to humans as well. Previous studies have shown a clear correlation between leptin and the time taken to run a marathon. Lower levels of leptin have been associated with higher physical performance.

“Our study with mice proposes that STAT3 is significantly involved in the satisfying effects experienced during and after physical exercise. We suggest that for humans, low levels of leptin increase the motivation to exercise and enhance the phenomenon of a ‘runner’s high’”, summarized Stephanie Fulton.

Bottom line: hormones send brain signals transmitting a clear message – food is limited, let’s go on an exciting run to find some!